The purpose of this study is to take into account the fact that the free semester system was piloted in 2013 and the free school in 2018, for the past five years, there have been few studies examining the trends of specific and systematic trends by analyzing the contents of the free semester system or by analyzing the content of research themes. Based on the domestic journals, this study was conducted to analyze the trends of the free semester using the Thematic Analysis of Content Analysis. In order to achieve the purpose of the study, 172 thesises were selected by the title keyword of ''Free Semester System'' through the Academic Research Service (RISS) except duplicated, non-related papers, and research reports.
In order to achieve the purpose of the study, the following research questions were selected.
Research problem 1: What are the study trends based on the frequency and percentage analysis of the basic items of the free semester system?
Research problem 2: What are the trends in the study related free semester through content analysis?
The research contents and method are as follows. In order to analyze the research trends related to the free semester system, it was classified into year, research type, methodology, linkage themes, and education subjects based on the analysis framework used in previous studies. The research papers were analyzed with 172 papers published in domestic journals to identify trends.

The results of this study are summarized as follows.
First, the study trends of research related the free semester system are steadily increasing from 2013 to 2018.
Second, classification by academic journals has been studied in various fields, but there is a lack of steady research.
Third, the result of analyzing research trends by a subjects in order to know the research trends related free semester system was thema-based education and convergence education papers were mostly studied.
Fourth, as a result of analyzing the papers by subjects in order to find out the research trends of the free semester system, the research papers related to student(56.1%) are higher than the research papers related to teacher(18.7%).
Fifth, In the analysis by research method, the program related research was the most dominant, the quantitative research, the qualitative research and the literature research were being studied well and the mixed research was found to be insignificant. Program-related research is declining every year.
Sixth, the research on the subject of free semester system was firstly related to the curriculum and teaching - learning method, among the researches related to curriculum and teaching - learning method, the most researches were conducted on teaching - learning method in detailed subject.
Seventh, the poor studies in the research trend by subjects of the study of free semester system are researches related to student evaluation, education management reflecting needs and demands of students and schools and analysis of curriculum, evaluation and status of teachers.

Therefore, this study will take as a preliminary resource for providing information from the selection of topics to the research process for free semester system related research, and it the furture will take as the basic data for stable settlement in the free semester system (free grade system). Suggesting that it is necessary to carry out a more detailed analysis study with methods and various subject classification methods.